In case you haven't heard of Minecraft, it is a 3D building type game where you can build whatever you can think of using just blocks. There is also a "survival mode" to the game where you build a house,look for resources such as wood, iron, coal and such. Monsters come out at night so you need to make a shelter and some weapons.
DS loves it because it's like a virtual Lego program.
So, for Halloween this past year he was a creeper from Minecraft and we made the costume out of boxes and took hours pasting construction paper squares on it.